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PMID: 10195374 Published · ppublish English Clinical Trial Comparative Study Journal Article Randomized Controlled Trial Research Support, Non-U.S. Gov't

Tyr-Ala-Hexarelin, a synthetic octapeptide, possesses the same endocrine activities of Hexarelin and GHRP-2 in humans.

Journal of endocrinological investigation ·Vol. 22 ·No. 2 ·1999-02-00 ·Pages 91-7

Arvat E, Di Vito L, Lanfranco F, Broglio F, Giordano R, Benso A, Muccioli GP, Deghenghi R, Ghigo E

Abstract

Hexarelin (HEX) and GHRP-2 are two synthetic hexapeptides, superanalogs of GHRP-6, belonging to GH secretagogue (GHS) family. GHS act via specific receptors at both the pituitary and the hypothalamic level to stimulate GH release both in animals and in humans. However, GHS also possess significant PRL- and ACTH/cortisol-releasing activity. Tyr-Ala-HEX as well as Tyr-Ala-GHRP-6 are, in turn, synthetic octapeptides generally used to perform binding studies because of their easy iodination. However, their endocrine activities have never been studied in humans. To clarify the endocrine activities of Tyr-Ala-HEX, in 7 young adult volunteers we compared the effects of the maximal effective dose of HEX (2.0 microg/kg i.v.) or GHRP-2 (2.0 microg/kg i.v.) with the same one of Tyr-Ala-HEX on GH, PRL, ACTH and cortisol levels. Basal GH, PRL, ACTH and cortisol levels in all testing sessions were similar. The administration of placebo did not modify hormonal levels. HEX and GHRP-2 administration induced the well known strong GH response (Cmax, mean+/-SE: 77.3+/-6.0 and 74.1+/-12.1 microg/l; AUC, mean+/-SE: 2596.7+/-251.1 and 2480.0+/-343.6 microg*min/l). These responses were similar to that induced by Tyr-Ala-HEX (63.7+/-18.5 microg/l; 1986.6+/-622.4 microg*min/l). Moreover, HEX, GHRP-2 and Tyr-Ala-HEX had the same significant stimulatory effect on PRL (14.9+/-2.5, 12.3+/-2.0 and 10.0+/-1.5 microg/l; 497.8+/-61.8, 480.4+/-66.9 and 415.8+/-58.5 microg*min/l), ACTH (48.0+/-10.1, 51.4+/-10.6 and 44.9+/-12.2 pg/ml; 1531.6+/-235.7, 1586.7+/-277.0 and 1338.1+/-164.5 pg*min/ml) and cortisol (179.9+/-10.0, 181.2+/-14.1 and 149.7+/-20.1 microg/l; 8465.0+/-406.6, 8689.2+/-788.1 and 6295.2+/-797.0 microg*min/l). Also the mean Tmax of the endocrine responses to HEX, GHRP-2 and Tyr-Ala-HEX were similar. In conclusion, the present results demonstrate that in humans Tyr-Ala-HEX is a GH secretagogue as potent as HEX and GHRP-2, two GHRP-6 superanalogs. Tyr-Ala-HEX also shares with HEX and GHRP-2 the same PRL- ACTH- and cortisol-releasing activity.

MeSH Terms
Adrenocorticotropic Hormone/blood Adult Female Growth Substances Human Growth Hormone/blood Humans Hydrocortisone/blood Kinetics Male Oligopeptides/administration & dosage,adverse effects,pharmacology Placebos Prolactin/blood
Chemicals
Growth Substances Oligopeptides Placebos tyrosyl-alanyl-hexarelin hexarelin Human Growth Hormone growth hormone releasing hexapeptide Adrenocorticotropic Hormone Prolactin Hydrocortisone
Authors & Affiliations
9 authors, click to expand affiliations / ORCID
Arvat E
Dipartimento di Medicina Interna, Università di Torino, Italy.
Di Vito L
Lanfranco F
Broglio F
Giordano R
Benso A
Muccioli G P
Deghenghi R
Ghigo E
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Article Info
Journal
Journal of endocrinological investigation
Abbr.
J Endocrinol Invest
ISSN
0391-4097
DOI
10.1007/BF03350886
Published
1999-02-00
Pages
91-7
Language
English
Region
Italy
NLM ID
7806594
Subset
IM
External Links
PubMed source DOI: 10.1007/BF03350886 View journal details
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